"I look forward to working with colleagues on this side of the chamber and indeed on the side opposite," he said.

"There will be times when I look forward to being tested by colleagues opposite and that, of course, is essential in any vibrant democracy.

"There is no doubt there will still be occasions in the future when there will be difficult times ahead both for politicians and politics and indeed for Wales.... I also look to see the assembly grow."

"It will take some getting used to to think of Rhodri as a back-bencher," he said

"He built his political reputation on being a very vocal back bencher (as an MP) and wasn't afraid to criticise the government in years gone by.

Carwyn Jones' family watched from the gallery as he was nominated

"I hope, of course, that's something he doesn't repeat in the future," he joked.

"I know that Rhodri will continue to play a very prominent part in this assembly - between now and the assembly elections and indeed beyond that," Mr Jones added.

Deputy First Minister and Plaid Cymru leader Ieuan Wyn Jones said: "I look forward to renewing our relationship with you in a different role to ensure that between now and the 2011 (assembly) election that we cooperate and collaborate for the benefit of the people of Wales."

Welsh Conservative leader Nick Bourne said he did not doubt Carwyn Jones's "personal and political commitment to the job in hand, and to serving Wales".

Welsh Liberal Democrat leader Kirsty Williams wished the first minister-elect and his family "a peaceful and restful Christmas and look forward to the challenges of the new year".

Carwyn Jones, a barrister by profession, is the AM for Bridgend and has held the posts of rural affairs minister and counsel general in Mr Morgan's administration.

He has pledged to increase spending on education, describing it as the route out of poverty.

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Live coverage of the Welsh Assembly

He also hopes to end "perceptions of isolation" in west and north Wales.

As Mr Morgan's resignation has been formally accepted, most special advisers have ceased to hold office, but ministers retain their jobs until an announcement on a new cabinet is made, expected on Thursday or Friday.

Following Mr Morgan's official announcement of his resignation during first minister's questions on Tuesday, leading politicians paid tribute to his achievements in office.

Presiding officer Lord Elis Thomas said Mr Morgan had held the trust of the Welsh people and brought "dignity and your unique trait to the office".

Deputy First Minister and Plaid Cymru leader Ieuan Wyn Jones said he had shown "great integrity", adding: "There's no doubt his contribution will be recognised by the history books."

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